Update from the Field: Perplexing Pollination Problems
Posted by Dave Dyson, Agronomist on August 13, 2018
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Over the last few weeks, the Cornbelt has seen above-normal temperatures and, in some areas, below-normal precipitation. Experiencing prolonged heat and moisture stress is not a good combination for the corn plant, especially during pollination and grain fill.
Peak pollen shed usually occurs in mid-morning, and a second shed of pollen often occurs in late afternoon or evening as temperatures cool. Pollen shed may occur throughout most of the day under relatively cool, cloudy conditions. Some research indicates pollen shed decreases after temperatures surpass 86 degrees Fahrenheit. As temperatures approach 100 degrees Fahrenheit, corn pollen can be killed. Corn pollen does not mature or shed all at once; pollen maturity and shed occur over several days and can last up to two weeks. Unfortunately, I have seen poor pollination in ears of corn this year, and I believe the heat and dry weather may have a hand in this.
The corn kernels are not out of the woods even after pollination is complete. Grain fill does not end until around 60 days after pollination, when the kernels are physiologically mature. Immature kernels are very sensitive to dry, hot weather. Corn kernels can be susceptible to kernel abortion or lightweight grain when the corn plant experiences stress during grain fill. Stress can include disease, weeds, and weather. As you can see in figure 1, this ear of corn had pollinated fully, but the kernels at the tip of the ear “pulled back” and aborted two-thirds of the kernels. This is very typical of stressed out corn.
Figure 1: Kernel abortion due to disease, heat, and drought stress. This picture was taken outside of Royal Center, IN 2018.
In conclusion, start scouting corn fields now! This is a great opportunity to prepare for any problems that may be happening out in the field. Stress can be a real drag on the yield, but fungicides and foliar fertilizers can alleviate the damage. Even if the corn is far enough along that a fungicide/foliar application would not help, consider adding these products for next year. Remember, when you reduce pressure from disease or nutrient deficiency, the corn plant is better equipped to handle adverse weather conditions without sacrificing yield.
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Dave Dyson is a regional agronomist for The Andersons’ Farm Centers which are located throughout Ohio, Michigan, and Indiana. He is an Indiana native and grew up on a dairy farm in Miami County. A graduate of Purdue University with a degree in Crop & Soil Science, Dave has a deep knowledge of various agronomic topics and is committed to helping growers improve their crops. If you have any questions, Dave can be reached at david_dyson@andersonsinc.com.
